1996 Nissan Terrano temperamental tacho

[Blackvcan]

Hey all - I do apologize for joining and instantly asking a question!

Okay - so a 1996 Nissan Terrano, the issue is a crazy tacho basically..

I have been trying to find somebody that is clued up in these cars, and thought "who has probably taken more of these apart than anyone else? Petrol heads into off roading!"
So, the issue that has arisen, is the Tacho, when you turn the truck on, the tacho jumps straight up to 8krpm, it corrects itself every now and then, but tends to stick to 8k. I thought I'd see if my diagnosis is a possibility..

I believe (emphasis on believe!) this could be due to the resistor on the back of the dash, as the tacho jumps straight to 8k, it seems that the tacho is still getting power, just not the power that it should be receiving.. So, based on that, it would seem that picking up a second hand gauge cluster (fingers crossed it's in good condition) this should fix the issue?

[BlakeNZ]

you neglected to say if you had a petrol or a diesel, as the tach signals are different between the two.

[BlakeNZ]

I'm picking you have the petrol V6 (the 8000 rpm was the clue). I'm thinking it sources the the RPM signal from the distributor? Do you have a distributor on that motor? Basicaaly three things are most likely. Some people suggest there is a resistor between the distributor and the tach, which can fault.(though some say this resistor doesn't exist) The next possibilty is a bad earth. An auto electrician can check this for you. Thirdly, and most likely , is a faulty Tach unit itself.

[Blackvcan]

Sorry! Wow bit of a brain fart.

TD27 Diesel (8k is the top top of the tacho)
A diagram is (hopefully) embedded below

[ChurchurDan]

Pull the tacho out and resolder the circuit board in it.

[icekayak]

Mine did the same thing, pulled it out and touched a soldering iron to each of the joints on the circuit board. Sure there was a writeup on it somewhere.

[MihiT]

Exactly as the two above posts. Check for continuity and cold solder joints on the tach daughterboard. My issue was a couple of cold joints and a poked diode.

[churchill]

Looks like a petrol engine tacho in a diesel engine vehicle! Never seen a diesel that revs that high.

[3VILC]

Yeah pretty sure mine only goes to 6 or 7 but definitely not 8, and the redline mark is more like 4500 not 6000